In the 1922 case Zucht v. King, Rosalyn Zucht challenged a San Antonio, Texas city ordinance that required proof of vaccination for public and private school students. She was excluded from school due to her failure to present a certificate of vaccination against smallpox. The Supreme Court upheld the constitutionality of compulsory vaccinations in schools as an exercise of police power aimed at protecting public health and safety. The court ruled that it is within the discretion of local authorities whether they would require immunization for children attending schools during times when there are no prevalent diseases or epidemics. This decision reaffirmed Jacobson v Massachusetts (1905), which established states' rights to enforce mandatory vaccination laws under their police powers.

In the case of Zucht v. King, there was no recorded dissenting opinion from any justice on the Supreme Court bench. The court unanimously upheld a San Antonio, Texas ordinance that required all children to be vaccinated against smallpox in order to attend public school or any other place where children are gathered together. The plaintiff argued that this violated her Fourteenth Amendment rights but the court disagreed and affirmed lower courts' rulings upholding the ordinance as a reasonable exercise of police power by states and municipalities for protection of public health.